Make appointments every hour, but not ON the hour

Hi! I'd like to be able to schedule appointments every hour from the my first available time, but not on the hour itself.

My available time is 9:30am-12:30pm, and I'd like to be able to offer 30 minute appointments every hour- at 9:30, 10:30, and 11:30.

Making them 60min appointments isn't feasible, because then clients will expect 60 minutes.

If I make the setting every 30 minutes with a 30 minute buffer, it still shows 9:30, 10, 10:30, 11... as the available slots.

The only workaround I've found is to block off time in my calendar to force OP to offer the slots I want, but this is creating a cluttered calendar.